This disclosure relates to migration of virtual machines or guests between hosts. In particular, it relates to handling migration of virtual machine that supports memory over commitment using one or more swap devices.
A guest machine, or a virtual machine, can be a virtual appliance, operating system or other type of virtualization-ready workload. From the view of the guest machine, it can function as a separate unit with its own dedicated resources. A hypervisor module can provide virtualization logic that manages one or more virtual machines. The hypervisor module (or just “hypervisor”) can assign shares of physical devices/hardware to the virtual machines that run on, and are managed by, the hypervisor. This virtualization can allow multiple virtual machines to run on top of a single physical host by sharing host resources between the multiple virtual machines. Some computer systems allow for multiple hypervisors to be run on their hardware.
Certain systems can allow for virtual machines to be migrated between different hypervisors. For instance, a planned hypervisor outage (e.g., to perform maintenance on a hypervisor) may trigger a migration event that causes one or more virtual machines to be migrated to another hypervisor. Satisfactory coordination between the source and target instances of the virtual machines can be difficult.